Insights on the volcanic and impact histories of the lunar nearside from the petrology, geochemistry, and geochronology of the Calcalong Creek lunar regolith breccia meteorite

The Calcalong Creek lunar meteorite is a regolith breccia with a lithologically diverse array of clasts set in a glassy, highly vesicular matrix. Here, we present a comprehensive new analysis of the meteorite. Comparisons to remote sensing data, lunar sample lithologies, and lunar sample ages indicate that it was likely sourced from regolith surrounding the Moon's nearside Procellarum KREEP Terrane, as opposed to the farside South Pole-Aitken basin as has been previously suggested. Partial and complete reset dates of ~3.9 Ga suggest a disturbance at this time, which aligns with that of the Imbrium basin-forming event, and to a lesser degree we see evidence of a ~4.2 Ga impact, which may be related to the formation of the Serenitatis basin. Analysis of Calcalong Creek clasts, thus, provide insights not only on the timing of major impact basin formation but also on the volcanic history of the Moon. The meteorite also samples some ancient ~4.3 Ga evolved magmatism, manifested in the presence of granophyre clasts, which may have originated from a high-μ, KREEP-like source, as well as younger, ~3.7 Ga low-Ti basaltic magmatism.